Trying to get the most out of my current set up

[harleyman1975]

2003 Regal 2000 (20') bowrider 2 8' 6" beam 3400 lbs dry 40 gal tank I/O 305 2 bbl mercruiser Alpha one gen max hp offered 280
normally 4-6 ppl primary use is pleasure (not much skiing or tubing) Deep Vee 20 degrees of deadrise 1.5 ratio
4400-4800 WOT range
no tabs or hydrofoil Quicksilver Nemesis Propeller Black Finish, 14 dia x 19 pitch, Right Hand
RPM _4600__________ Speed ___47________ No. of people _____2_______ Gal. Gas ___20_____
1100' elevation no damage to prop engine running perfect tuned up 20 hrs ago
put current prop on to improve hole shot and bring rpms up into suggested range (with 14.5x21 3 blade only turning 4350 WOT 48 mph)

Will 19x3 al give more top end? would stainless make a difference? anything I can do to improve holeshot ? (short of more horsepower or bravo 3)

 

[alldodge]

If I read info correctly
19-4 blade, 4600 rpm. 1.5 ratio. 47 mph = 14.82 slip
A 4 blade prop is close to two inch pitch higher 3 blade

with 21 p 14.5x19 3 blade only turning 4350 WOT

Understand the WOT rpm = 4350 but I'm assuming that this is using a 21-4 blade, but do not know the speed

A 19-3 blade should increase the rpm around 4800. Stainless blades are thinner and do not flex as much

 

[harleyman1975]

There see if that is easier to understand...I fixed a couple of typos/omissions. It was a touch faster with 21 p 3 blade but it was lugging and struggled out of the hole.

 

[alldodge]

The extended editing allows for all kinds of fixes
You went from a 19-4 blade to a 21-3 blade and lost 250 rpm and gained 1 mph which increased the slip to 16.77

The 21 is only 1/2 inch more diameter then the 19 so this should not normally have had that mush of a change. Is the 21 cupped?

 

[jimbo_jwc]

Most my friends are running the Solas Prop 4 blade 14.25 x 18 its great all round on a 196 CC , my favorite is a old SS 3 blade 19 '" square hole vented without any rubber reducer hole inserts .. My 5.0l 228 likes 15" X 17" but not sure if it only fits pre alpha 1 , it old fiberform 23' and heavy with command bridge .

 

[QBhoy]

Mmm
This is a difficult one. Going by your figures, a good 19" 3 blade like a laser 2 should see you right.
I must admit, I'm surprised you are only turning those revs with the engine and gear ratio quoted...perhaps the 4 blade would explain this. I'd defo try a 19" 3 blade good stainless.
Is the ratio defo 1.47 ?

 

[Scott Danforth]

I would run a 15x19p stainless. I had a Solas on my searay and the prop was perfect. The 21 is too much pitch

 

[harleyman1975]

Thanks for the feedback guys. I did run the boat this weekend and at 3500 I'm doing 30 gps, at 3000 Im doing 24 gps with the 19 pitch 4 blade. Local prop shop has offered to let me try a 19 pitch 3 blade which I will try this weekend...maybe even stainless. My guy says to stay with quicksilver props on a mercury...Might just be his opinion...But I'm sure he knows more about it than I do. lol

 

[alldodge]

I think his QS comment is opinion, but I have no issue with the props and use them my self.

The 19-4 has you slip at 28 percent

 

[harleyman1975]

Wont it get worse if I go to 3 blade?

 

[alldodge]

Wont it get worse if I go to 3 blade?

No, what your doing right now is turning to much prop. The 19-4 is like a 21-3, its lugging your motor, you need to get the rpms up. Now you may have some other things going on, but need to get you closer to your WOT rpm to determine what else may be needed

 

[harleyman1975]

I can get close to 4800 WOT with the 19/4 blade. That is in the sweet spot for a 305 2bbl isn't it? I get so many different answers when I ask about redline for this motor. some say 4400-4800, some say 4600-5000, still others say 4800-5200...I very rarely run it that hard. Mostly hang around 3000-3500. I'd never run my truck over 4800...